Flash Sale Eligibility

A flat request describes one candidate product: productId and category identify it, currentInventory and profitMargin cover the economics, season and currentMonth handle timing, and sellerRating with sellerHistoricalSales profiles the merchant. The schema marks all eight fields as required.

Stock and margin are screened together with a first hit policy: 50 or more units with a profitMargin of at least 0.25 passes as 'Sufficient inventory and margin', and 100 or more units passes with a thinner 0.15 margin. Below that, fewer than 20 units fails as 'Insufficient inventory for flash sale', a margin under 0.1 fails as 'Margin too low for promotion', and the blank row rejects everything else, writing passesInitialCheck and initialCheckReason either way.

Flash sales spike demand, so the stock floor exists to avoid instant sellouts and the cancellations that follow, a standard concern when planning promotional volume. Accepting a lower 0.15 margin once inventory clears 100 units reflects clearance economics, where moving overstock justifies a thinner cut, while the 0.1 hard floor keeps any discounted sale from going out below cost.

Calendar fit is a lookup of season against currentMonth lists: 'summer' matches months 6, 7, 8, 'winter' matches 1, 2, 12, 'fall' matches 9, 10, 11, 'spring' matches 3, 4, 5, and 'all-year' products pass in any month. The blank fallback row sets isInSeason to false with the reason 'Product out of season'.

Tying promotion slots to the demand calendar is how retailers actually plan markdown and event cadences, since discounting a summer item in month 7 amplifies existing demand while the same discount in winter just erodes margin. The 'all-year' row keeps staple merchandise eligible without forcing a fake season onto it.

Seller signals compress into three values: isQualifiedSeller requires sellerRating >= 4.0 and sellerHistoricalSales >= 1000 together, seasonalityFactor becomes 1.2 in season versus 0.8 out, and sellerFactor grades 1.5 for qualified sellers, 1.0 for ratings of at least 3.5, and 0.5 below that. The isQualifiedSeller flag is what the eligibility table branches on next, including its top-seller exemption row.

Everything converges in a first hit table over passesInitialCheck, isInSeason, and isQualifiedSeller. All three true earns the full 15 discountPercentage as 'Product fully qualifies for flash sale', an in-season product without a qualified seller gets 10, a qualified seller off season gets 8, and a failed initial check can still salvage 5 through the 'Top seller exemption applied' row when isQualifiedSeller == true and currentInventory >= 30. The fallback row marks the product ineligible with a discount of 0.

Scaling discount depth with qualification strength is sound promotion economics: the deepest cut is only funded when inventory, margin, season, and seller quality all line up, and each missing factor shaves the offer rather than killing it. The exemption row is a sensible business choice to keep proven sellers in the program, with its own 30-unit floor so the override never books a sale the stock cannot cover.